Method and apparatus for manufacturing metal material, metal material and metal workpiece

ABSTRACT

To easily prevent adhesion of molten metal at low costs without deteriorating surface quality in a metal material manufacturing method by continuous casting. In continuously casting a metal material S 1  by driving a plurality of rotational molding members  10, 11  in a casting direction, the plurality of rotational molding members  10, 11  being disposed so as to be opposed with each other to form a casting space, lubricating oil is intermittently sprayed onto at least a part of a molten alloy contact surface of at least one of the plurality of rotational molding members  10  or  11.

This application claims priority to Japanese Patent Applications No.2004-272664 filed on Sep. 21, 2004, No. 2005-129348 filed on Apr. 27,2005, No. 2005-233654 filed on Aug. 11, 2005, No. 2005-233664 filed onAug. 11, 2005, U.S. Provisional Application No. 60/605,167 filed on Aug.30, 2004 and U.S. Provisional Application No. 60/613,228 filed on Sep.28, 2004, the entire disclosures of which are incorporated herein byreference in their entireties.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is an application filed under 35 U.S.C. §111(a)claiming the benefit pursuant to 35 U.S.C. §119(e)(1) of the filing dateof U.S. Provisional Application No. 60/605,167 filed on Aug. 30, 2004and U.S. Provisional Application No. 60/613,228 filed on Sep. 28, 2004,pursuant to 35 U.S.C. §111(b).

FIELD OF THE INVENTION

The present invention relates to a method for manufacturing a metalmaterial by continuous casting, a manufacturing apparatus for executingthis manufacturing method, a metal material manufactured by themanufacturing method and a metal workpiece manufactured from the metalmaterial.

DESCRIPTION OF THE RELATED ART

In continuously casting a metal wire rod, a continuous casting apparatusis used. The continuous casting apparatus is provided with a pluralityof rotation molding members arranged opposite with each other so as toform a casting space therebetween. These rotation molding members aredriven in a casting direction while supplying molten metal in thecasting space to continuously manufacture a metal cast material. Forexample, in a Properzi type casting apparatus, a rotation molding memberin which a casting wheel with a groove on its external peripheralsurface and an endless belt for closing the groove are combined is used.

In such rotation molding member, in order to prevent adhesion of moltenmetal, casting is performed while applying lubricating oil to the innersurface of the rotation molding member, or a lubricating layer is formedon the inner surface of the rotation molding member (see PatentDocuments 1, 2 and 3).

In a method in which lubricating oil is applied, lubricating oil issprayed with a spraying apparatus utilizing a negative pressuregenerated by airflow or a lubricating oil impregnated fiber cloth ispressed against the inner surface of the rotation molding member. Assuch lubricating oil, chemical synthesis oil or vegetable oil such asricinus high in heat resistance is used.

As to a method for forming such lubricating layer on the inner surfaceof the rotation molding member, Patent Document 1 proposes that alubricating layer of graphite fluoride is formed on the inner surface byapplying liquid in which graphite fluoride powder is dispersed inalcohol to a molding surface, or by dispersing graphite fluoride in ametal plating layer to be formed on the molding surface. Furthermore,Patent Document 2 proposes a lubricating layer to which soot generatedby incomplete combustion of acetylene gas adheres, and Patent Document 3proposes that a lubricating layer is formed by thermally spraying fireresistance ceramic.

Furthermore, in the aforementioned continuous casting, a rolling machineis disposed at the rear stage of the rotation molding member, so that ametal cast material can be continuously rolled into a cast rolledmaterial of a desired configuration.

In some cases, however, the surface of such cast rolled material maydarken, resulting in deteriorated surface quality as compared with anextruded material. The visually recognized darkening of the surface canbe, e.g., carbide or oxide. The carbide is generated from lubricatingoil used to prevent adhesion of molten metal to a molding member bybeing exposed to high temperature. The oxide is mainly MgO generatedfrom Mg among additive elements contained in the surface layer of thecast rolled material by being oxidized because metal material is castand held at high temperatures.

Under the circumstances, there are proposed methods in which the surfaceof the cast rolled member is removed by cutting or cleaned by sprayingpressurized water subsequent to the rolling process (see Patent Document4).

[Patent Document 1] Japanese Unexamined Laid-open Patent Publication No.S59-18048

[Patent Document 2] Japanese Unexamined Laid-open Patent Publication No.S53-123333

[Patent Document 3] Japanese Unexamined Laid-open Patent Publication No.S59-174254

[Patent Document 4] Japanese Unexamined Laid-open Patent Publication No.S50-159423

DISCLOSURE OF THE INVENTION

[Problems to be Solved by the Invention]

Although sufficient adhesion prevention effect can be attained byforming a thin oil film, excessive lubricating oil was applied since itwas difficult to apply small amount of lubricating oil by theaforementioned methods for applying lubricating oil at the time ofcontinuous casting. There are problems that such excessive amount oflubricating oil causes not only deterioration of the surface quality ofthe metal cast material such as the darkening of the surface but also anincreased lubricating oil cost.

On the other hand, in the method for forming a lubricating layer ofgraphite fluoride as disclosed in Patent Document 1, the lubricatinglayer can be decomposed at high temperatures, resulting in a shortenedduration of effect, which in turn causes further increased cost ascompared with the case in which lubricating oil is applied. In the caseof forming a lubricating layer of soot as disclosed by Patent Document 2or forming the lubricating layer of refractory ceramic as disclosed byPatent Document 3, there also is a problem that the cost for forming thelubricating layer is expensive.

Further, also in a method for removing the darkening of the cast rolledmaterial surface, there are problems that the surface cutting removal ispoor in material yielding and raises both the material cost and themanufacturing cost since the cutting processing is performed separately.Furthermore, the surface purification by water spraying as disclosed inPatent Document 4 has a problem that sufficient cleaning effects cannotbe obtained.

[Means to Solve the Problems]

The present invention was made in view of the above-identified technicalbackground, and aims to provide a method for manufacturing a metalmaterial with excellent surface quality, wherein the method can easilyprevent adhesion of molten metal at low costs without causingdeterioration of cast material surface quality, or further can removethe surface darkening.

In order to attain the aforementioned object, the method formanufacturing a metal material according to the present invention hasthe following structure as recited in the following Items [1] to [24].

[1] A method for manufacturing a metal material, characterized in that

in continuously casting a metal material by driving a plurality ofrotational molding members in a casting direction, the plurality ofrotational molding members being disposed so as to be opposed with eachother to form a casting space,

wherein lubricating oil is intermittently sprayed onto at least a partof a molten alloy contact surface of at least one of the plurality ofrotational molding members.

[2] The method for manufacturing a metal material as recited in theaforementioned Item 1, wherein the plurality of rotational moldingmembers are a casting wheel having a groove on its external peripheralsurface and a continuous belt for closing the groove.

[3] The method for manufacturing a metal material as recited in theaforementioned Item 2, wherein the lubricating oil is applied to thegroove of the casting wheel.

[4] The method for manufacturing a metal material as recited in theaforementioned Item 3, wherein the lubricating oil is applied only to aside surface portion of the groove of the casting wheel.

[5] The method for manufacturing a metal material as recited in theaforementioned Item 2, wherein the lubricating oil is applied to thecontinuous belt.

[6] The method for manufacturing a metal material as recited in theaforementioned Item 1 or 2, wherein the spraying number of times T persecond is set to V/(Lp+V×t) to 3V/(Lp+V×t), where V (mm/s) is a movingspeed of a molten alloy contact surface of the rotational moldingmember, t (s) is a single spraying time, Lp (mm) is a distance of asprayed range in a casting direction, the sprayed range being formed bya single spraying in a state in which the rotational molding member isstopped.

[7] The method for manufacturing a metal material as recited in theaforementioned Item 1 or 2, wherein the spraying of the lubricating oilis performed by a plunger pump.

[8] The method for manufacturing a metal material as recited in theaforementioned Item 1 or 2, wherein a single spraying time is 0.001 to1s.

[9] The method for manufacturing a metal material as recited in theaforementioned Item 1 or 2, wherein a single spraying amount is 0.001 to1 ml.

[10] The method for manufacturing a metal material as recited in theaforementioned Item 1 or 2, wherein a total spraying amount of thelubricating oil is 5 to 150 ml/h.

[11] The method for manufacturing a metal material as recited in theaforementioned Item 1, wherein subsequent to the continuous casting,rolling is executed to manufacture a cast rolled material, and whereinthe cast rolled material is subjected to multi-stage washing includingacid washing or caustic washing.

[12] The method for manufacturing a metal material as recited in theaforementioned Item 11, wherein the multi-stage washing is performedwhile moving the cast rolled material.

[13] The method for manufacturing a metal material as recited in theaforementioned Item 12, wherein the multi-stage washing is performedsubsequent to the continuous casting and the rolling.

[14] The method for manufacturing a metal material as recited in theaforementioned Item 12, wherein the multi-stage washing is performed ata different step after the continuous casting and the rolling.

[15] The method for manufacturing a metal material as recited in theaforementioned Item 11, wherein the multi-stage washing is performedafter cutting the cast rolled material.

[16] The method for manufacturing a metal material as recited in theaforementioned Item 11, wherein the multi-stage washing includes atleast one caustic washing and at least one acid washing.

[17] The method for manufacturing a metal material as recited in theaforementioned Item 16, wherein the multi-stage washing is performed bycaustic washing and acid washing in this order.

[18] The method for manufacturing a metal material as recited in theaforementioned Item 16, wherein the multi-stage washing is performed byacid washing, caustic washing and acid washing in this order.

[19] The method for manufacturing a metal material as recited in theaforementioned Item 11, wherein washing liquid for the acid washing isany one of nitric acid, sulfuric acid and hydrochloric acid.

[20] The method for manufacturing a metal material as recited in theaforementioned Item 11, wherein washing liquid for the caustic washingis sodium hydrate solution or potassium hydrate.

[21] The method for manufacturing a metal material as recited in theaforementioned Item 11, wherein washing time for the acid washing or thecaustic washing is controlled by a time required for the cast rolledmaterial to pass through each washing bath.

[22] The method for manufacturing a metal material as recited in theaforementioned Item 11, wherein the washing bath passing time is set bya length of a washing bath in a moving direction of the cast rolledmaterial.

[23] The method for manufacturing a metal material as recited in theaforementioned Item 21 or 22, wherein the washing bath passing time isset by a serpentine distance along which the continuous cast rolledmaterial is advanced in a washing bath.

[24] The method for manufacturing a metal material as recited in theaforementioned Item 11, wherein water washing is performed after theacid washing or the caustic washing.

The apparatus for manufacturing a metal material according to thepresent invention has the following structure as recited in thefollowing Items [25] to [27].

[25] An apparatus for manufacturing a metal material, comprising:

a plurality of rotational molding members disposed so as to surround acasting space and driven in a casting direction; and

lubricating oil spraying means for intermittently spraying thelubricating oil to at least a part of at least a part of the rotationalmolding members.

[26] The apparatus for manufacturing a metal material as recited in theaforementioned Item 25, further comprising rolling means for rolling thecast material, the rolling means being disposed at a rear stage of therotational molding members, and a plurality of washing baths includingan acid washing bath which brings the rolled cast rolled material intocontact with acid washing liquid or a caustic washing bath which bringsthe cast rolled material into contact with caustic washing liquid,wherein these washing baths are disposed in series.

[27] The apparatus for manufacturing a metal material as recited in theaforementioned Item 26, wherein at least one acid washing bath whichbrings the cast rolled material into contact with the acid washingliquid and at least one caustic washing bath which brings the castrolled material into contact with the caustic washing liquid areprovided.

The metal material according to the present invention has the followingstructure as recited in the following Item [28].

[28] A metal material manufactured by the manufacturing method asrecited in the aforementioned Item 1 or 11.

A metal workpiece according to the present invention as recited in Item[29] and [30] has the following structure.

[29] A metal workpiece manufactured by subjecting the metal member asrecited in the aforementioned Item 28 to secondary working.

[30] The metal workpiece as recited in the aforementioned Item 29,wherein as the secondary working, plastic working or cutting work isexecuted.

[Effects of the Invention]

According to the manufacturing method of a metal member of the presentinvention as recited in the aforementioned Item [1], an appropriateamount of lubricating oil can be applied to the rotational moldingmember in continuous casting to prevent adhesion. Furthermore, surfacequality deterioration due to excessive lubricating oil can be prevented,which makes it possible to manufacture a metal member excellent insurface quality. Furthermore, since the timing or application sprayingamount of the lubricating oil is controlled, the method can be performedat low costs.

According to the invention as recited in the aforementioned Item [2], ina continuous casting using a casting wheel and a continuous belt forclosing a groove of the casting wheel as rotational molding members, theaforementioned effects can be attained.

According to the invention as recited in the aforementioned Item [3],the aforementioned effects can be attained to the groove of the castingwheel.

According to the invention as recited in the aforementioned Item [4],the amount of the lubricating oil can be reduced while attaining theaforementioned effects to the groove of the casting wheel.

According to the invention as recited in the aforementioned Item [5],the aforementioned effects can be attained to the continuous belt.

According to the invention as recited in the aforementioned Item [6],the spraying ranges can be continued.

According to the invention as recited in the aforementioned Item [7], aminute amount of lubricating oil can be evenly applied.

According to the invention as recited in the aforementioned Item [8], aminute amount of lubricating oil can be evenly applied.

According to the invention as recited in the aforementioned Item [9], aminute amount of lubricating oil can be evenly applied.

According to the invention as recited in the aforementioned Item [10],an appropriate amount of lubricating oil can be applied.

According to the invention as recited in the aforementioned Item [11],by executing multi-stage washing including acid washing or causticwashing, surface darkened portions of the cast rolled material can beremoved to thereby manufacture a metal member with good surface quality.

According to the invention as recited in any one of the aforementionedItems [12] to [14], since the cast rolled material is continuouslywashed, the productivity is high, which in turn makes it possible toreduce the costs. Especially, in the invention as cited in the Item[13], the productivity is high since the washing is performed on thecontinuous cast rolling line.

According to the invention as recited in the aforementioned Item [15],since a number of cast rolled materials can be washed simultaneouslyunder the same conditions, it is hardly affected by the pH of thewashing liquid and/or the fluctuations of the liquid temperatures, andtherefore the step administration can be performed easily. Furthermore,the setting and/or changing of the washing conditions can be easilyperformed.

According to the invention as recited in any one of the aforementionedItems [16] to [20], excellent washing effects can be attained.

According to the invention as recited in any one of the aforementionedItems [21] to [23], washing time can be adjusted.

According to the invention as recited in the aforementioned Item [24],it becomes possible to prevent the washing liquid from being carriesover the subsequent stage.

According to the manufacturing apparatus of a metal material of theinvention as recited in any one of the aforementioned Items [25] to[27], a metal material excellent in surface quality can be manufacturedby executing the manufacturing method as recited in Item [1] or [11].

The metal material as recited in the aforementioned Item [28] isexcellent in surface quality.

According to the metal workpiece as recited in the aforementioned Item[29], any configuration can be obtained from the metal material asrecited in Item [18].

According to the invention as recited in the aforementioned Item [30],any configuration can be obtained from the metal material as recited inItem [28] by subjecting it to plastic working and/or cutting work.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic view showing a structure of a manufacturingapparatus (continuous casting apparatus) for executing the method formanufacturing a metal material according to the present invention.

FIG. 2 is a partially enlarged view showing the principle portion ofFIG. 1.

FIG. 3A is a view showing a spraying range in a stopped state.

FIG. 3B is a view showing a spraying range in a moving state.

FIG. 4A is a view showing an intermittent spraying state in a movingstate.

FIG. 4B is a view showing another intermittent spraying state in amoving state.

FIG. 5 is a schematic cross-sectional view showing a nozzle and aplunger pump.

FIG. 6 is a block diagram showing an example of a structure of alubricating oil spraying controlling apparatus.

FIG. 7 is a schematic structural view of the metal materialmanufacturing apparatus provided with a rolling portion and a cleaningportion.

FIG. 8 is a cross-sectional view showing rolling steps of a castmaterial.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

In a method for manufacturing a metal material according to the presentinvention, in continuous casting, an appropriate amount of lubricatingoil is applied to a molten alloy contact surface of a rotational moldingmember by intermittently spraying the lubricating oil. Furthermore, inthis method for manufacturing a metal material according to the presentinvention, the metal material continuously cast by the aforementionedmethod is rolled subsequent to the casting, and the cast rolled materialis washed at multi-stages.

Hereinafter, [A] a method for intermittently spraying lubricating oilonto a rotational molding member during continuous casting and [B] amethod for cleaning the cast rolled material at multi-stages will bedetailed with reference to an apparatus for executing these methods. Inthe following explanation, a metal material manufactured by continuouscasting but not rolled yet will be referred to as “cast material” or“cast material (S1),” and a metal material manufactured by continuouscasting and then rolled will be referred to as “cast rolled material” or“cast rolled material (S2).”

[A] Method for Intermittently Spraying Lubricating Oil onto RotationalMolding Member During Continuous Casting

FIGS. 1 and 2 schematically show a continuous casting apparatus 1 forcarrying out the method.

This continuous casting apparatus 1 is provided with a casting wheel 10and a continuous belt 11 as rotational molding members.

The casting wheel 10 is provided with a groove 12 on its externalperipheral surface, and is capable of being cooled with cooling watersupplied through nozzles 13 a provided in the wheel 10 and nozzles 13 barranged outside the wheel 10. The continuous belt 11 is a circularendless belt put on the casting wheel 10 and a tension adjusting wheel14, so that the belt 11 closes the groove 12 of the casting wheel 10 tothereby form a casting space 15. The continuous belt 11 can be cooled bysupplying cooling water from outside thereof or can be heated byarranging a heater outside thereof.

Lubricating oil is sprayed onto the groove 12 of the casting wheel 10through the nozzle 16 of a spraying apparatus. Furthermore, lubricatingoil is also sprayed onto the continuous belt 11 through the nozzle 17 ofthe spraying apparatus. Thus, the lubricating oil can be sprayed ontoany desired portion of the inner surface of the casting space 15. Thisspraying of the lubricating oil through the nozzles 16 and 17 isintermittently carried out in predetermined cycles.

In FIG. 1, the reference numeral “18” denotes a pinch roller forbringing the continuous belt 11 into close contact with the castingwheel 10, and “19” denotes a tundish for supplying the molten metal M tothe casting space 15.

In the continuous casting apparatus 1, the molten metal M supplied fromthe tundish 19 to the casting space 15 is continuously formed into acast material S1 by being cooled by the casting wheel 10 and thecontinuous belt 11 in accordance with the rotational movements thereofwhile solidifying from the contacting surface of the molten alloy M incontact with the casting wheel 10 and the continuous belt 11. Since thelubricating oil is applied to the inner surface of the casting space 15,the adhesion of the molten metal can be prevented, resulting in easydetachment of the cast material S1.

The spraying cycles of the lubricating oil are preferably set asfollows, based on the moving speed of the molten metal contactingsurface of the rotational molding member, the single spraying range, thesingle spraying time, etc so that the lubricating oil is notdiscontinuously supplied and excessively applied.

As shown in FIG. 3A, the nozzle 16, 17 sprays lubricating oil roundly ata diffusion angle θ°, and is disposed at a height of “h” (mm) from themolten metal contacting surface of the rotational molding member, i.e.,the groove 12 of the casting wheel 10 or the continuous belt 11. Underthe aforementioned nozzle conditions, the spray range P1 becomes acircular shape with a diameter of 2 h tan[θ/2] (mm) in a stopped state,and the distance Lp (mm) of the spray range P1 along the castingdirection is the same 2 h tan[θ/2] (mm) as the diameter. In the case inwhich the groove 12 and the continuous belt 12 move at a moving speed V(mm/s) and a time required for one spray is “t” (s), the groove 12 andthe continuous belt 12 move by a distance V×t (mm) during one spray.Since the spray is being continued during this movement, the spray rangeP2 in the moving state of the rotational molding members becomes anelongated circular shape with a major axis of Lp+V×t(mm). Accordingly,the distance of the spray range P2 along the casting direction in themoving state is Lp+V×t (mm) (see FIG. 3A).

As will be understood from the above, in intermittently sprayinglubricating oil through the nozzle 16 and 17, spray ranges P2 can bearranged in a continuous manner with no gap therebetween as shown inFIG. 4A, provided that the spraying number of times T per second isrepresented by V/(Lp+V×t), wherein V (mm/s) is a moving speed of themolten metal contacting surface of the rotational molding members, t (s)is a spray time per one spray, and Lp (mm) is a distance of the sprayrange per one spray along the casting direction when the rotationalmolding member is in a stopped state. If the spraying number of times Tbecomes fewer than V/(Lp+V×t), non-sprayed portions will be generated inthe casting direction. On the other hand, as shown in FIG. 4B, as thespraying number of times T increases, the overlapped portion P3 of thespray ranges P2 increases. When the number of spray times T reaches 1/t,a continuous spray can be attained. However, such continuous spraycauses an excessive application of the lubricating oil, and thereforethe present invention excludes such continuous spraying. As an upperlimit of the spraying number of times per second which does not cause anexcessive application of the lubricating oil, it is preferable to set to3V/(Lp+V×t). As a result, it is preferable that the spraying number oftimes T per second is set so as to fall within the range of fromV/(Lp+V×t) to 3V/(Lp+V×t). Furthermore, as shown in FIG. 4B, theoverlapping of the spray ranges 2 can decrease the non-applied portionin the widthwise direction. Therefore, it is more preferable that thespraying number of spray times T per second falls within the range offrom V/(Lp+V×t) to 2V/(Lp+V×t).

In the meantime, the spray range P1 is round in a stopped state as shownin the figure. This causes non-applied portions in the widthwisedirection at the time of the actual intermittent sprays. Therefore, itis preferable to set the spraying number of times T such that thespraying number of spray times T is larger than V/ (Lp+V×t) to causeoverlapped portions P3 and that the length of the overlapped portion P3in the casting direction is equal to or longer than Lp/2. In this state,no non-applied portion occurs and excessively applied portions can bedecreased. In the meantime, the configuration of the spray range is notlimited to the circular shape as illustrated, and the configuration andarea of non-applied portions change depending on the sprayconfiguration. Accordingly, the spraying number of times T can bearbitrarily set depending on the configuration of the spray range so asnot to cause non-applied portions excessively.

In spraying the lubricating oil, it is preferable to employ a sprayingmeans capable of constantly spraying a small amount of the lubricatingoil to attain an even and thin application. As a preferable example ofsuch spraying means, a lubricating oil supplying apparatus using aplunger pump 20 as shown in FIG. 5 can be exemplified. The plunger pump20 is configured to discharge lubricating oil introduced into a cylinder23 via a one-way valve 21 a from a lubricating oil tank 22 in accordancewith reciprocal movements of a plunger 24 fitted in the cylinder 23 witha motor 25 or the like. One discharge amount is controlled by the strokelength of the plunger 24, and the time required for the single dischargeis controlled by the stroke length of the plunger 24 and the strokevelocity thereof. The lubricating oil discharged from the cylinder 23 issupplied to the spraying nozzle 16, 17 via a tubular passage 26. Thenozzle 16, 17 has a dual structure in which an inner tube for supplyingthe lubricating oil discharged from the plunger pump 20 is disposed inan outer tube 27 in which compressed gas is introduced with the fore-endof the inner tube 28 opened in the outer tube 27. The lubricating oilsupplied to the inner tube 28 of the nozzle 16, 17 is accelerated bybeing mixed with the compressed gas at the fore-end portion of the outertube 27 to be sprayed at a high speed from the nozzle end. In FIG. 5,the reference numeral “21 b” denotes a one-way valve for preventing thereverse flow of the lubricating oil.

Although the type of the gas is not specifically limited, it ispreferably to prevent the use of flammable gas in view of the fact thatit is used near molten alloy. In terms of costs, air can be used mostpreferably. Examples of such gas also include nitrogen and argon.

In the aforementioned spraying apparatus comprising the lubricating oilsupplying apparatus equipped with the plunger pump 20 and the nozzle 16,17 having a dual structure, the total spraying amount of the lubricatingoil is controlled by the single discharging amount by the plunger pump20 and the number of times of the discharging, and the compressed gasfor increasing the flow velocity can be controlled independent from thelubricating oil amount. As a result, a small amount of the lubricatingoil can be sprayed constantly at high flow velocity, and it is alsopossible to finely adjust the flow rate. By increasing the flowvelocity, it is also possible to remove foreign substances adhering tothe rotational molding member. It is also possible to control thecooling effect by the gas flow by controlling the gas flow rate, whichin turn can control the temperature of the rotational molding member.For example, the temperature deterioration can be enhanced with theenhanced cooling effect by increasing the flow rate. To the contrary,the temperature deterioration can be suppressed by decreasing the flowrate. In adjusting the temperature, the gas flow rate can be adjustedwithout changing the amount of the lubricating oil.

According to other spraying methods such as a spraying method utilizingnegative pressure, the viscosity of lubricating oil and/or the gasdensity may change depending on changes in atmospheric pressure and/ortemperature, resulting in fluctuations of spraying amount. Furthermore,although it is required to decrease the gas flow to decrease thespraying amount, the decreased gas flow may cause insufficient negativepressure, which makes it difficult to absorb the lubricating oil and/orcauses unstable absorbing amount of the lubricating oil. Furthermore, itis easily affected by the atmospheric air flow because of the slow flowrate, and therefore there is a possibility that the lubricating oilsprayed against the rotational molding member fails to reach thepredetermined position. In view of the above mentioned drawbacks, it isrecommended to employ the aforementioned spraying method using a plungerpump 20.

A single spraying time of the lubricating oil preferably falls withinthe range of from 0.001 to 1 second. If it is less than 0.001 second,the spraying range becomes too small, resulting in poor thin and evenapplication effect by intermittent sprays. On the other hand, a sprayingtime exceeding 1 second is not realistic in view of operation of aspraying apparatus such as a pump. It is more preferable that a singlespraying time is 0.005 to 0.1 second.

A single spraying amount of the lubricating oil preferably falls withinthe range of from 0.001 to 1 ml. A single spraying amount less than0.001 ml is not realistic in view of operation of a spraying apparatussuch as a pump. On the other hand, if it exceeds 1 ml, the applicationamount becomes excessive. The more preferable spray amount is 0.002 to0.1 ml.

The total application amount of the lubricating oil preferably fallswithin the range of from 5 to 150 ml. If it is less than 5 ml/h, moltenmetal adhesion preventing effect becomes insufficient. To the contrary,if it exceeds 150 ml/h, an excessive amount of lubricating oil issupplied, resulting in waste of lubricating oil. It is more preferablethat the total application amount is 5 to 100 ml/h, still morepreferably 5 to 50 ml/h. The preferable range of the total applicationamount differs depending on the application area.

In the lubricating oil spraying apparatus using a plunger pump 20 asshown in FIG. 5, the gas flow rate preferably falls within the range offrom 1 to 30 l/min. If it is less than 1 l/min, it is difficult to makethe lubricating oil adhere to the rotational molding member. To thecontrary, if it exceeds 30 l/min, the rotational molding member iscooled excessively, cracks may occur on the surface of the cast materialdue to the quick cooling. If it falls within the aforementioned range,sufficient flow velocity to make the lubricating oil adhere can beattained and excessive cooling of the rotational molding member can beavoided. The most preferable gas flow rate is 2 to 20 l/min.

In this invention, the lubricating oil used at the time of continuouscasting is not specifically limited. Well know lubricating oil such asricinus can be used. However, in order to attain smooth high speedspraying in a short time, it is preferable to use lubricating oil low inviscosity. The preferable viscosity of the lubricating oil is 0.1 to 5Pa·s, more preferably 0.3 to 2 Pa·s.

In the aforementioned embodiment, although the lubricating oil issprayed onto the entire molten alloy contacting surface of therotational molding member, such lubricating oil can be sprayed onto anyone of rotational molding member among a plurality of combinedrotational molding members, or the lubricating oil can be sprayed onto apart of the molten alloy contacting surface of a rotational moldingmember because of the following reasons. Depending on the configurationof the rotational molding member, there exists a portion to which themolten alloy easily adheres, a portion to which the molten alloy neveradheres, and a portion to which the molten alloy hardly adheres.Therefore, the purpose can be attained by applying the lubricating oilonly to portions where adhesion occurs. Application only to thenecessary portions simplifies the lubricating oil cleaning after thecasting and decreases the consumption amount of the lubricating oil.Furthermore, even in cases where rolling is performed after casting,generation of blackening due to the lubricating oil can be decreased.

In the aforementioned continuous casting using the casting wheel 10 andthe continuous belt 12, the adhesion tends to occur at the side surface12 a of the groove 12 of the casting wheel 10. Hereinafter, referring tothe lubricating oil spraying control apparatus shown in FIG. 6, anexample of spraying the lubricating oil onto both side surfaces 12 a and12 a of the groove 12 will be explained together with the controlmethod.

In FIG. 6, two lubricating oil spraying nozzles 16 are disposed with thenozzles facing toward both side surfaces 12 a of the groove 12 of thecasting wheel 10. Each of these nozzles 16 is a nozzle of the same dualstructure type as that shown in FIG. 5 for spraying the lubricating oilsupplied from the plunger pump 20 by being mixed with a compressed gas.The reference numeral “30” denotes a calculation-control apparatus whichoutputs a control signal to a motor 25 for driving the plunger pump 20and flow rate adjusters 33 for adjusting the flow rate of the gascompressed by the compressor 32, based on the revolution speed X1 of therevolution axis of the casting wheel 10 measured by a sensor 31 attachedto the axis and another inputted conditions. In detail, based on themeasured revolution speed X1 of the casting wheel 10 and the set wheelexternal diameter, the moving speed V of the side surface portion 12 ato which the lubricating oil is to be sprayed is calculated.Furthermore, based on the set spraying diffusion angle θ, the distance hfrom the molten alloy contacting surface to the fore-end of the nozzle16 and the single spraying time (single spraying time by the plungerpump 20), the distance Lp of the single spraying range in the castingdirection and the spraying number of times T of the spraying per secondare calculated. Based on these calculated values, the control signal X2is given to the motor 25. Thus, a constant amount of the lubricating oilis discharged from two plunger pumps 20 at the rate of T times persecond to be introduced in the inner tube of the dual hose 35 a viarespective tubular passages 34 a . On the other hand, to the two flowrate adjusters 33, the control signal X3 is given based on the set gasflow rate. Thus, a certain flow amount of the compressed air isdischarged and introduced into the external tube of the dual hose 35 avia the respective tubular passages 36a. The inner and outer tubes ofthe dual hose 35 a are communicated with the inner pipe 28 and the outerpipe 27 of each nozzle 16. The lubricating oil and compressed gassupplied to the nozzle 16 via the dual hose 35 a will be mixed at theinner fore-end side of the external tube 27 and sprayed at high speed.

The spraying control method of the lubricating oil is not limited to thespraying to the side surface portion 12 a of the groove 12. Byarbitrarily changing the number of nozzles 16 and the positions, thelubricating oil can be sprayed onto the bottom portion 12 b of thegroove 12, the continuous belt 11, or any portion of another rotationmolding member. In cases where a plurality of nozzles are used, sprayingunder different conditions every nozzle can be attained by disposing theplunger pump and the flow rate adjusters in a separate system.

Since the moving speed of the continuous belt 11 in the aforementionedcontinuous casting apparatus 1 is almost the same as the peripheralspeed of the casting wheel 10, the moving speed of the groove 12calculated from the revolution speed X1 of the casting wheel 10 can beused as the moving speed of the continuous belt 11 as it is.Accordingly, without measuring the moving speed of the continuous belt11, the lubricating oil to be sprayed from the nozzle 17 can becontrolled via the tubular passages 34 b and 36 b and the dual hose 35b.

In the meantime, there is a casting method for moving the finalsolidification portion from the central portion of the cast material tothe vicinity of the surface thereof by causing temperature difference inthe rotational molding member to thereby differentiate thesolidification rates (hereinafter referred to as “directionalsolidification” or “continuous casting method by directionalsolidification”). In the case of the continuous casting apparatus 1,when a cast material S1 is continuously cast by a directionalsolidification method while cooling the casting wheel 10 and heating thecontinuous belt 11, the vicinity of the cast material in contact withthe continuous belt 11 becomes the final solidification portion to besegregated. In general, cast defects such as shrinkage cavities and/orhot cracks tend to occur in the final solidification portion. If a castmaterial with hot cracks near the surface is rolled, the cracks grow andbecome deeper. In such case, removing the final solidification portionat the side of the continuous belt 11 before the rolling prevents thegrowth and increase of the cracks. Furthermore, in cases where minutecracks or foreign substances exist in the surface, the removal of thesurface portion prevents the growth of the cracks and/or the involvementof the foreign substance. In the cast material of directionalsolidification, an easy removal of the surface portion can be executedsince the final solidification portion exists near the surface.

In the continuous casting by the directional solidification too, byexecuting the intermittent spraying method for applying the lubricatingoil according to the present invention, the continuous belt 11 will notbe cooled excessively and the lubricating oil will not be dried toadhere. Thus, the continuous casting can be performed in an optimalmanner. Furthermore, by controlling the single spraying amount of thelubricating oil, the spraying number of times per second and the singlespraying time, the aforementioned effects can be easily attained.

In the directional solidification, it is preferable that the heatingtemperature of the continuous belt falls within the range of from[liquidus temperature of the casting metal×0.35] to [liquidustemperature].

The rotational molding member to which the method of the presentinvention is applied is not limited to a combination of the castingwheel and the continuous belt. Examples of another rotational moldingmembers include a pair of rollers opposed with each other at a certaindistance in parallel to the rotational axis. The present invention isnot limited to the continuous casting method in which the lubricatingoil is intermittently sprayed to all of the rotational molding members,but also can be applied to the case in which the lubricating oil isintermittently applied only to some of rotational molding members. Forexample, in the illustrated rotational molding member, the case in whichthe lubricating oil is intermittently sprayed onto either one of thegroove 12 of the casting wheel 10 and the continuous belt 11 can beexemplified. Accordingly, the present invention includes the case inwhich the lubricating oil is intermittently sprayed to some of therotational molding members while continuously spraying the lubricatingoil to anther rotational molding members or forming a lubricating oillayer on another rotational molding members.

According to the aforementioned method, since an appropriate amount oflubricating oil can be applied to the rotational molding member, theadhesion of lubricating oil can be prevented assuredly. Furthermore,surface quality deterioration due to excessive lubricating oil can beprevented, which makes it possible to manufacture a metal memberexcellent in surface quality. Since the concrete work is a control ofthe spraying timing and/or the application amount of the lubricatingoil, the application of the lubricating oil can be carried out at alower cost as compared with the method of forming a lubricating layer asdisclosed by the aforementioned Patent Documents 1 to 3. Furthermore,since the excessive amount of the lubricating oil is not applied,darkening due to the lubricating oil can be decreased, resulting an easyremoval operation of the darkening.

Since the method of the present invention makes the amount oflubricating oil to be sprayed onto the rotational molding memberappropriate, the method can be carried out by changing the sprayingconditions of the existing lubricating oil spraying means or by adding alubricating oil spraying means capable of intermittently spraying thelubricating oil to the existing continuous casting apparatus. The methodcan be easily performed without requiring large scale apparatus changessuch as changing of rotational molding members and/or the controlapparatus.

[B] Method for Cleaning Cast Rolled Member at Plural Stages

This method includes a rolling step for manufacturing a cast rolledmember by executing the rolling subsequent to the continuous casting anda washing step for washing the cast rolled member at plural stages, inaddition to the step of continuously casting the cast material whileintermittently spraying the lubricating oil. On the surface of the castrolled member, the lubricating oil is adhering, though the amount isminimized by the intermittent spraying. Therefore, the surface isdarkened by the carbide due to the lubricating oil and the oxidegenerated during the casting and the rolling. This method intends toremove the surface darkening of the cast rolled member by plural stagecleaning to thereby improve the surface quality of the cast rolledmember.

The step of continuously casting a cast material as a first step is thesame as the step explained in the method of intermittently spraying thelubricating oil to the rotational molding member in the aforementioned[A] continuous casting. Accordingly, the explanation of this step willbe omitted.

At the rolling step as a second step, a rolling apparatus is disposed ata rear stage of the continuous casting apparatus in which rotationalmolding members are combined, and the rolling is executed subsequent tothe continuous casting. Examples of the rolling method include theso-called properch method, a SCR method, a hunter method, a 3C method,and a roll-cast method. The configuration of the cast rolled member tobe formed is not specifically limited. As to the cast rolled member,although a member round in cross-section and a plate member are common,the present invention does not limit the cross-sectional shape and thesize such as a cross-sectional diameter and a thickness. Furthermore,the present invention can also be applied to a modified cross-sectionalmember in addition to the member round in cross-section and the platemember.

At the washing step as the third step, the cast rolled member is washedat plural stages. The multi-stage washing can be performed while movingthe cast rolled member (hereinafter “continuous washing”) or aftercutting the cast rolled member (hereinafter “batch washing”).Furthermore, the continuous washing can be performed continuously afterthe cast rolling, and also can be performed after the cast rolling atanother steps.

Hereinafter, the continuous washing and batch washing will be detailed.

[Continuous Washing]

FIG. 7 shows an example of a metal material manufacturing apparatus 2for executing three steps of casting, rolling and washing in acontinuous fashion.

This manufacturing apparatus 2 includes a continuous casting apparatus1, a rolling portion 40, and a washing portion 50.

The continuous casting apparatus 1 is the continuous casting apparatusshown in FIGS. 1 and 2 including the nozzles 16 and 117 forintermittently spraying the lubricating oil onto the casting wheel 10and the continuous belt 11.

The rolling portion 40 includes a plural pairs of three-directionalrollers 41. FIG. 7 illustrates only two-directional rollers.

In the washing portion 50, a first acid washing bath 51, a causticwashing bath 52, and a final acid washing bath 53 are arranged in thisorder. Immediately after each washing bath 51, 52, 53, a water washingbath 54, 55, 56 are arranged. After the rear stage of these baths, adrying bath 57 is arranged.

In the continuous casting apparatus 1, a cast material S1 of aprescribed cross-section is continuously formed in accordance with therotational driving of the casting wheel 10 and the continuous belt 11 ina state in which the lubricating oil is intermittently being sprayedthrough the nozzles 16, 17 onto the casting wheel 10 and the continuousbelt 11. As shown in FIG. 8, the cast material S1 is rolled into a castrolled material S2 with a small diameter round in cross-section by therolling portion.

At the washing portion 50, the cast rolled material S2 is subjected tothe acid washing-the water washing-the caustic washing-the waterwashing-the acid washing-the water washing while passing through eachbath 51, 54, 52, 55, 53, 56 in order, and the water adhering to thesurface is removed to be dried in the drying bath 57. During thesesteps, oxides and/or carbides formed in the surface portion of the castrolled material S2 and recognized as darkened portions are removed.Thus, a line material excellent in surface quality is manufacturedconsecutively.

In this method, by executing the multi stage washings including the acidwashing and the caustic washing, metallic oxides and/or carbides formedon the surface of the cast rolled material can be removed appropriately,resulting in cast rolled material excellent in surface quality.Furthermore, since the lubricating oil used at the time of continuouscasting is minimized, contamination of the washing liquid can beminimized, and the washing time and the consumption amount of thewashing liquid can be minimized.

The aforementioned effects can be attained by executing the multi-stagewashing including either the acid washing or the caustic washing.However, the combination of different washings of two types, the causticwashing and the acid washing, more effective washing effects can beattained. Especially, it is preferable to execute the acid washing, morepreferably two-stage washing of the caustic washing and the acidwashing, as the final washing. Furthermore, as explained in theaforementioned embodiment, by executing three-stage washing in which theacid washing is added before the caustic washing, more excellent washingeffect can be attained. Furthermore, adding the acid washing makes itpossible to shorten the subsequent caustic washing time.

The multi-stage washing in the present invention is not limited to theaforementioned two-stage washing or three-stage washing, any combinationthereof can be allowed. For example, the present invention allows acidwashing-caustic washing, caustic washing-acid washing-caustic washing,multi-stage washing only including acid washings, multi-stage washingonly including caustic washing and four-stage or more multi-stagewashing. In addition to the acid washing and the caustic washing,washing using surfactant can be added.

The washing can be executed by immersing the cast rolled material in thewashing liquid or spraying the washing liquid against the cast rolledmaterial. In the case of the immersion washing, it can be performed bymerely filling the washing liquid in a bath. However, the washing can beenhanced by preventing the accumulation of the washing liquid whichcomes into contact with the surface of the cast rolled material. As tothe accumulation preventing means, circulation of the washing liquid inthe bath and collecting/re-supplying of the overflowed washing liquidcan be exemplified. Furthermore, adding supersonic vibration can enhancethe washing effect.

After the acid washing and the caustic washing, it is preferable toexecute the water washing without carrying over the previous washingliquid into the subsequent water washing bath.

As the washing liquid for the acid washing, from the view point ofexcellent washing effects, nitric acid, sulfuric acid, phosphoric acid,acetic acid, hydrochloric acid, fluorinated acid and combination thereofcan be exemplified. Nitric acid, sulfuric acid or hydrochloric acid canbe preferably used. Among other things, nitric acid or sulfuric acid canbe more preferably used. The pH of the washing liquid is preferably 5 orless, more preferably 1 to 3. The liquid temperature is preferably 20 to80° C.

As the washing liquid for the caustic washing, from the view point ofexcellent washing effects, sodium hydroxide solution or sodium hydroxidesolution, or combination thereof can be exemplified. Among other things,sodium hydroxide solution can be preferably used. The pH of the washingliquid is preferably 9 or above, more preferably 12 to 14. The liquidtemperature is preferably 20 to 80° C.

The washing time for the acid washing and the caustic washing is notspecifically limited, and can be arbitrarily set considering thedarkening degree of the cast rolled material surface, the pH of thewashing liquid and the liquid temperature. It is preferable to addadditive agent to the acid washing liquid or the caustic washing liquidto improve the washing effects. For example, in the case of the causticwashing, a small amount of sodium gluconate can be added to prevent hardscale when the molten metal becomes supersaturation. Furthermore, afterthe acid washing and the caustic washing, it is preferable to executethe water washing without carrying over the washing liquid to thesubsequent washing bath.

In the case of continuous washing, the traveling speed of the castrolled material is controlled by the cast rolling speed, and thereforeit is required to execute the washing the cast rolled material at therate. Accordingly, the washing time at each washing stage is set by thetime in which the cast rolled material is in contact with the washingliquid, i.e., the time required that the cast rolled material passes thewashing bath. Concretely, a method of setting the time depending on thewashing bath length in the traveling direction of the cast rolledmaterial and a method of setting the time depending on the serpentinedistance along which the cast rolled material is traveled along theserpentine pass can be exemplified.

Furthermore, the washing of the cast rolled member can be executed aftercooling it to a normal temperature, but the washing can be executed athigh temperature (e.g., 400° C.).

In cases where the washing is executed in a state in which the castrolled member is still high in temperature, since the washing liquid isheated by being contacted by the high temperature cast rolled materialeven if the washing liquid is normal in temperature, the same effects asin the case in which a heating apparatus is equipped with the washingbath can be attained. In this case, the pH of the washing liquid maychange largely due to the evaporation of the water content at eachwashing bath. In such a case, the optimal pH (optimal concentration) canbe maintained by supplying water arbitrarily and stirring/circulatingthe washing liquid. Providing a water cooling bath before the initialwashing bath can suppress the pH changes of the washing liquid due tothe water content evaporation in the subsequent acid washing bath orcaustic washing bath. Furthermore, providing a cooling apparatus at eachwashing bath can prevent temperature rise due to the heat of the castrolled material and/or the reaction heat. In cases where the prescribedwashing liquid temperature is lower than the room temperature, a heatingapparatus such as a heater can be arbitrarily provided.

In the aforementioned continuous washing, since the surface washing iscontinuously executed on the line of the continuous cast rolling, theproductivity is high, which in turn can lower the costs.

In cases where multi-stage washing is executed at a step different fromthe continuous cast rolling step, the cast rolled material wounded intoa coil is passed through the aforementioned multi-stage washing bathswhile rewinding the coil. Each washing time can be arbitrarily adjustedby the length of the washing bath and the serpentine distance in thesame manner as mentioned above. Even in cases where the multi-stagewashing is executed at another step, sufficiently high productivity canbe attained as compared with a conventional darkened portion removingmethod by surface cutting.

[Batch Washing]

In cases where batch washing of the cast rolled material is executed,the multi-stage washing is executed after cutting the cast rolledmaterial into a prescribed length.

The manufacturing of the cast rolled material is performed by, forexample, a cast rolling apparatus including a continuous casting portion1 and a rolling portion 40 according to the aforementioned manufacturingof the cast rolled material in the continuous washing. The cutting canbe executed subsequent to the cast rolling or while unwinding the coiledmaterial.

The multi-stage washing can be executed by a batch method at eachwashing bath, and the type of washing liquid, pH, temperature setting,combination of washing liquids and the washing order can be executedaccording to the aforementioned continuous washing.

According to the batch washing, since a number of cast rolled materialscan be washed simultaneously under the same conditions, it hardly beaffected by the pH of the washing liquid and the liquid temperaturefluctuations, and the step administration can be performed easily.Furthermore, since the batch washing is executed at a step differentfrom the cast rolling step, the setting or changing of the washingconditions can be performed easily.

The metal material production method according to the present inventioncan be applied to every metal continuous casting (including the caseswhere multi-washing is executed). It can be preferably applied to thecontinuous casting of aluminum or its alloy, cupper or its alloy. Amongother things, it can be preferably applied to aluminum or its alloycontinuous casting. As aluminum or its alloy, pure Al series alloy,Al—Cu series alloy, Al—Si series alloy, Al—Mg series alloy, Al—Mg—Siseries alloy, and Al—Zn—Mg series alloy can be exemplified. Especially,in the case of aluminum alloy other than pure aluminum series, since asegregation layer can be easily formed on the surface thereof, in thecontinuous casting method by the directional solidification, the effectsby intermittently applying lubricating oil according to the presentinvention can be effectively attained.

Since the metal material of the present invention is a cast material orcast rolled material manufacture by the aforementioned method and anappropriate amount of lubricating oil is applied to the rotationalmolding member at the time of the continuous casting, the casting can beexecuted while assuredly preventing the adhesion. Furthermore, sinceconcrete manufacturing operations are controlling of the timing and theapplication amount of the lubricating oil, the operations can beexecuted at low costs as compared with the case in which eachlubricating layer is formed as disclosed by the Patent Documents 1 to 3previously mentioned. Furthermore, in the cast rolled material to whichthe multi-stage washing is executed, the surface darkened portions areremoved, resulting in metal material excellent in surface quality.

Furthermore, a metal work piece of any configuration can be obtained bysubjecting the aforementioned metal material secondary working. As suchsecondary working, rolling, extruding, drawing, forging, bending andpressing can be exemplified. Furthermore, the metal material can bearbitrarily subjected to more than two types of plastic working such asdrawing after rolling sequentially. Also, cutting work can be executedafter plastic working. The product configuration is not limited. Thesemetal work pieces have healthy metal surface since foreign substancessuch as carbides due to metal oxides and/or lubricating oil have beenremoved from the surface portion thereof.

The metal material manufacturing apparatus according to the presentinvention is provided with at least the aforementioned plural rotationalmolding members and lubricating oil spraying means, and can also beprovided with the aforementioned rolling portion and the washing portionif necessary. The structure of the remaining means such as molten alloysupplying means and cast material/cast rolled material transferringmeans is not specifically limited and can be any well knownmean/structure.

To the metal material manufactured by the method of the presentinvention, various steps can be arbitrarily executed. For example, byadding a rolling portion including one pair or plural pairs of millrolls at a rear stage of the continuous casting apparatus, the metalmaterial can be rolled subsequent to the casting into a prescribedconfiguration. In other words, this structure is a washing portionomitted structure, and it is a cast rolled manufacturing method with nomulti-stage washing. Furthermore, at the rear stage of the continuouscasting apparatus, a cutting portion for cutting the surface layerportion of the cast material can be arbitrarily added. In general,although defects such as minute cracks, segregation layers, uneven oxidefilms exit in a surface portion of a cast material, by executing thesurface layer portion cutting subsequent to continuous casting, suchdefects can be removed to improve the quality of the cast material.Furthermore, by the cutting, a final solidification portion formed atthe vicinity of the surface by the aforementioned directionalsolidification can also be removed. Furthermore, at the rear stage ofthe continuous casting apparatus, a cutting portion and a rollingportion can also be provided. By this structure, casting, surface layerportion removing and rolling can be executed continuously. Needless tosay, after the rolling, the multi-stage washing of the present inventioncan be combined.

EXAMPLES

[A] Intermittent Spraying of Lubricating Oil in Continuous Casting

Using the continuous casting apparatus 1 as shown in FIGS. 1 to 3B, acontinuous casting test according to JIS A6061 was executed. In thecontinuous casting apparatus 1, a casting wheel 1 with a diameter of1,400 mm and a groove cross-sectional area (cross-sectional area of thecasting space 15) of 2,200 mm² was used, and a continuous belt 11 with awidth of 100 mm was used.

As a lubricating oil spraying nozzle 16, 17, a dual structure nozzle forspraying lubricating oil discharged from the plunger pump 20 shown inFIG. 5 and mixed with compressed gas was used. As the lubricating oil tobe supplied to the inner tube 28 of the nozzle 16, 17, ricinus(viscosity: 0.680 pa·s) was used. As the compressed gas to be suppliedto the external tube 27, air was used.

Furthermore, the lubricating oil and compressed gas to be supplied tothe nozzle 16, 17 were controlled by the lubricating oil controlapparatus as illustrated in FIG. 16. Please note that FIG. 6 exemplifiesa structure in which two nozzles 16 for the casting wheel and one nozzle17 for the continuous belt are controlled by one motor 25 under the sameconditions for convenience of explanation. However, in this example, thenumber of nozzles was changed depending on the following spraying tests,and the number of motors, the control signal system and the tubularpassages were changed so that the lubricating oil and the compressed gascould be supplied to every nozzle.

[Spraying Test I]

One lubricating oil spraying nozzle 16 was disposed before the moltenalloy supplying portion of the casting wheel 10, and one lubricating oilspraying nozzle 17 was disposed before the molten alloy contact portionof the continuous belt 11 was supplied. The casting wheel side nozzle 16was disposed perpendicular to the groove 12 and the distance from thebottom surface 12 b of the groove 12 to the fore end of the nozzle 16,17 was set to 50 mm, to spray the lubricating oil against both sideportions 12 a and the bottom surface portion 12 b of the groove 12.Furthermore, the continuous belt side nozzle 14 was disposedperpendicular to the continuous belt 11, and the distance from themolten alloy contact surface of the continuous belt 11 to the fore endof the nozzle 16, 17 was set to 50 mm. The spraying angle θ of thenozzle 16, 17 was adjusted to 45°, and the nozzle was adjusted so thatthe spraying configuration becomes round.

Initially, in the continuous casting apparatus, when the casting wheel10 was driven at 1 rpm, and the single spraying time t was set to 0.1 s,a minimum number T of times of spraying per second in which the sprayingranges are continuously formed in the moving direction of the groove 12and continuous belt 11 was obtained.

The moving speed V of the casting wheel 10 and the continuous belt 11can be represented by V=1400×p/60=73.3 mm/s.

The spraying range P1 at the stopped state becomes a circle with adiameter of 2 h tan θ/2=2×50×tan(45°/2)=41.4 mm. The diameter Lp is adistance in the casting direction of the spraying range P1.

The distance L in the casting direction of the spraying range P2 at themoving state is L=Lp+V×t=41.4+73.3×0.1=48.7 mm.

Accordingly, since T=V/(Lp+V×t)=73.3/48.7=1.5 s⁻¹, the minimum number Tof times of spraying to make the sprayed ranges P2 continue at themoving state is 1.5 times per second.

Next, the revolution number of the casting wheel 10 was set to 1 rpm, asingle splaying amount of each nozzle 16, 17 was set to 0.005 ml, asingle spraying time t was set to 0.1 s, and the flow amount of thecompressed gas was set to 7 l/min. The casting tests were executed whilechanging the number of time of spraying, and the adhesion at the time ofthe casting and the surface quality of the cast material S1 wereevaluated. The evaluation results are shown in Table 1. TABLE 1 Sprayingconditions of the casting wheel and the continuous belt Single sprayingtime t = 0.1 s, Single spraying amount: 0.005 ml Spraying Total numberof sprayed amount* No. times times/s ml/h Evaluation I-1 1 18 Adhesionoccurred due to oil film break I-2 1.2 21.6 Slight adhesion occurred I-31.5 27 No adhesion occurred, casting surface was good I-4 2 36 Noadhesion occurred, casting surface was good I-5 4 72 No adhesionoccurred, casting surface was good I-6 8 144 No adhesion occurred, butconsumption amount of lubricating oil was large I-7 Continuous 180 Noadhesion occurred, but spraying consumption amount of lubricating oilwas large*Each total sprayed amount at the casting wheel and the continuous belt

Furthermore, single spraying amount of each nozzle 16, 17 was set to0.005 ml, single spraying time was set to 0.2 s, the flow amount of thecompressed gas was set to 7 l/min. The casting tests were executed whilechanging the number of time of spraying, and the adhesion at the time ofthe casting and the surface quality of the cast material S1 wereevaluated. The evaluation results are shown in Table 2. TABLE 2 Sprayingconditions of the casting wheel and the continuous belt Single sprayingtime t = 0.2 s, Single spraying amount: 0.005 ml Number of times ofTotal spraying sprayed amount* No. times/s ml/h Evaluation I-8  0.5 9Adhesion occurred due to oil film break I-9  1 18 Slight adhesionoccurred I-10 1.5 21.6 No adhesion occurred, casting surface was goodI-11 2 27 No adhesion occurred, casting surface was good I-12 4 36 Noadhesion occurred, casting surface was good I-13 Continuous 90 Noadhesion occurred, but spraying consumption amount of lubricating oilwas large*Each total sprayed amount at the casting wheel and the continuous belt[Spraying Test II]

Two nozzles 16 were disposed before the molten alloy supplying portionof the casting wheel 10 with the nozzles facing to both side surfaceportions 12 a of the groove 12 as shown in FIG. 6. The distance h fromeach nozzle 16 to the fore end was set to 30 mm, so that the lubricatingoil was sprayed only to both side surface portions 12 a of the groove12. The spraying angle θ of the nozzle 16 was adjusted to 30°, and thenozzle was adjusted so that the spraying configuration becomes round.

Before the molten alloy supplying portion of the continuous belt 11, inthe same manner as in the aforementioned spraying test I, one nozzle 17was disposed so that the distance h to the fore end of the nozzle was 50mm. The spraying angle θ of the nozzle 17 was adjusted to 45°, and thenozzle was adjusted so that the spraying configuration becomes round.

When the revolution number of the casting wheel 10 was set to 1 rpm, asingle spraying time t was set to 0.1 s, the spraying range P1 at thestopped state and the spraying range P2 at the moving state in themoving direction of the groove 12 and the continuous belt 11, a minimumnumber of times T of spraying per second to make the sprayed rangescontinue was shown in Table 3. TABLE 3 Revolution number of castingwheel: 1 rpm (V = 73.3 mm/s) Single spraying time t: 0.1 s GrooveContinuous belt Distance h from sprayed 30 mm 50 mm surface to nozzlefore end Spraying angle θ 30° 45° Sprayed range P1 at Circle withdiameter Circle with diameter stopped state Lp of 16.1 mm Lp of 41.4 mmSprayed range P2 at Distance L in casting Distance L in casting movingstate direction: 23.4 mm direction: 48.7 mm Minimum number of 3.2 1.5times T to make sprayed ranges P2 continue

Next, the revolution number of the casting wheel 10 was set to 1 rpm, asingle splaying amount of each nozzle 16 was set to 0.001 ml, a singlespraying time t was set to 0.1 s, and the flow amount of the compressedgas was set to 5 l/min. A single splaying amount of the continuous beltside nozzle 17 was set to 0.005 ml, a single spraying time t was set to0.1 s, and the flow amount of the compressed gas was set to 7 l/min. Thecasting tests were executed while changing the number of time ofspraying, and the adhesion at the time of the casting and the surfacequality of the cast material S1 were evaluated. The evaluation resultsare shown in Table 4. TABLE 4 Groove Continuous belt Single sprayingtime = 0.1 s Single spraying time = 0.1 s Single spraying Singlespraying amount: 0.001 ml × 2 amount: 0.005 ml Gas flow rate: 5 l/minGas flow rate: 7 l/min No. of times of Total sprayed No. of times ofTotal sprayed spraying amount* spraying amount* No. times/s ml/h times/sml/h Evaluation II-1 1 7.2 1 18 Adhesion occurred due to oil film breakII-2 2 14.4 1.2 21.6 Slight adhesion occurred II-3 3.2 23.0 1.5 27 Noadhesion occurred, casting surface was good II-4 4 28.8 2 36 No adhesionoccurred, casting surface was good II-5 8 57.6 4 72 No adhesionoccurred, casting surface was good II-6 16 11.5 8 144 No adhesionoccurred, but consumption amount of lubricating oil was large II-7Continuous 72 Continuous 180 No adhesion spraying spraying occurred, butconsumption amount of lubricating oil was large*Total sprayed amount of two nozzles

Next, the revolution number of the casting wheel 10 was set to 1 rpm, asingle splaying amount of the groove side nozzle 16 was set to 0.001 ml,a single spraying time t was set to 0.2 s, and the flow amount of thecompressed gas was set to 10 l/min. A single splaying amount of thecontinuous belt side nozzle 17 was set to 0.005 ml, a single sprayingtime t was set to 0.2 s, and the flow amount of the compressed gas wasset to 7 l/min. The casting tests were executed while changing thenumber of time of spraying, and the adhesion at the time of the castingand the surface quality of the cast material S1 were evaluated. Theevaluation results are shown in Table 5. TABLE 5 Groove Continuous beltSingle spraying time = 0.2 s Single spraying time = 0.2 s Singlespraying Single spraying amount: 0.001 ml × 2 amount: 0.005 ml Gas flowrate: 10 l/min Gas flow rate: 7 l/min No. of times of Total sprayed No.of times of Total sprayed spraying amount* spraying amount* No. times/sml/h times/s ml/h Evaluation II-9 1 3.6 0.5 9 Adhesion occurred due tooil film break II-10 2 7.2 1 18 Slight adhesion occurred II-11 3 8.6 1.521.6 No adhesion occurred, casting surface was good II-12 4 10.8 2 27 Noadhesion occurred, casting surface was good II-13 8 14.4 4 36 Noadhesion occurred, but consumption amount of lubricating oil was largeII-14 Continuous 36 Continuous 90 No adhesion spraying sprayingoccurred, but consumption amount of lubricating oil was large*Total sprayed amount of two nozzles

From the results shown above, it is confirmed that intermittent sprayingof lubricating oil prevents adhesion and enables continuously casting ofa cast material with good casting surface. Furthermore, it is alsoconfirmed that applying lubricating oil only to the side surfaceportions of the groove where adhesion tend to occur enables reducedconsumption amount of lubricating oil while preventing occurrence ofadhesion.

[B] Multi-Stage Washing of Cast Rolled Material

Using the metal material manufacturing apparatus 2 equipped with thecontinuous casting apparatus 1, the rolling portion 40 and the washingportion 50, surface washing tests were performed subsequent to theproduction of the cast rolled material. The washing baths 51 to 57 ofthe washing portion 50 were decreased in number and/or changed inposition depending on the washing step, and the metal materials wereimmersed in the washing liquid of each washing bath for a certain amountof time.

In the following washing test A to E and comparative washing test, usingcast material of JIS A6061, cast materials S1 polygon in cross-sectionwere manufactured while intermittently spraying lubricating oil onto thecasting wheel 10 and the continuous belt 11. As shown in FIG. 8, at therolling portion 10, the cast material S1 was rolled into a roundbar-shaped rolled material S2 with a diameter of 30 mm. Lubricating oilfor the continuous casting was intermittently sprayed to both sidesurface portions 12 a of the groove 12 of the casting wheel 10 and thecontinuous belt 11 under the same conditions as in Example No. II-4shown in Table 4. That is, the spraying conditions of the groove sidenozzle 16 were: single spraying time t: 0.1 s, single spraying amount:0.001 ml (per nozzle), spraying number of times: 4 times/s, gas flowrate: 5 ml/min. The spraying conditions of the continuous belt sidenozzle were: single spraying time t: 0.1 s, single spraying amount:0.005 ml, spraying number of times: 2 times/s, gas flow rate: 7 ml/min.

[Washing Test A]

Among the washing baths shown in the washing portion 50, using thecaustic washing bath 52, the water washing bath 55, the final acidwashing bath 53, and the water washing bath 56, the cast rolled materialS2 were subjected to the caustic washing and the acid washing under theconditions shown in Table 6, and the dried. The adjustment of thewashing time was performed by adjusting the cast rolling speed. TABLE 6Final acid washing Darkened Caustic washing Washing portion Washingliquid Washing time conditions removal rate % A-1 50° C. 3 min Room 90A-2 pH13 4 min temperature, 100 A-3 sodium 5 min pH1 nitric acid 100hydrate 1 min washing[Washing Test B]

Caustic washing and acid washing were performed while changing thewashing liquid and the washing time as shown in Table 7 which weredifferent from those in Washing test A. The washing time adjustment wasperformed by adjusting the cast rolling speed and changing the washingbath length.

In the washing, the caustic washing bath 52 was preheated to 50° C. witha heater, and then held at 50° C. by the heater. However, when the castrolled material S2 was passed through the washing tank 52 at a hightemperature of 200° C., the power consumption of the heat during thepassing was halved as compared with the case in which the temperaturewas held at 50° C. TABLE 7 Caustic washing Final acid washing DarkenedWashing Washing Washing Washing portion liquid time liquid time removalrate % B-1 50° C. 15 sec Room 15 sec 95 B-2 pH 13 30 sec temperature 30sec 100 sodium pH 1 hydrate sulfuric acid[Washing Test C]

Using all of the washing baths of the washing portion 50, or the firstacid washing bath 51, the water washing bath 54, the caustic washingbath 52, the water washing bath 55, the final acid washing bath 53, andthe water washing bath 56, the cast rolled material S2 was subjected tothe fist acid washing, the caustic washing and the acid washing usingthe washing liquid shown in Table 8 and then dried. The washing timeadjustment was performed by adjusting the cast rolling speed andchanging the washing bath length. TABLE 8 First acid Final acid Darkenedwashing Caustic washing washing portion Washing Washing Washing Washingremoval conditions liquid time conditions rate % C-1 Room 50° C., 1 minRoom 100 C-2 temperature, pH 13 2 min temperature, 100 pH 1 nitricsodium pH 1 nitric acid acid 1 min hydrate 1 min washing washing[Washing Test D]

The first acid washing, caustic washing and acid washing were performedwhile changing the conditions as shown in Table 9 which were differentfrom those in Washing test C. The washing time adjustment was performedby adjusting the cast rolling speed and changing the washing bathlength. TABLE 9 Darkened First acid washing Caustic washing Final acidwashing portion Washing Washing Washing Washing removal Washing liquidtime liquid time Washing liquid time rate % D-1 Room 15 sec 50° C. 15sec Room 15 sec 95 D-2 temperature 30 sec pH 13 30 sec temperature 30sec 100 pH 1 sulfuric sodium pH 1 sulfuric acid acid hydrate[Washing Test E]

Among the washing baths shown in the washing portion 50, using the acidwashing bath 51, the water washing bath 54, the caustic washing bath 52,and the water washing bath 55, the cast rolled material S2 was subjectedto the acid washing and the caustic washing under the conditions shownin Table 10, and the dried. The adjustment of the washing time wasperformed by adjusting the cast rolling speed. TABLE 10 Darkened Causticwashing Caustic washing portion Washing Washing Washing removal Washingliquid time liquid time rate % E-1 Room 1 min 50° C., 1 min 90temperature, pH 13 pH 1 nitric acid sodium hydrate E-2 Room 1 min 50°C., 2 min 100 temperature, pH 13 pH 1 nitric acid sodium hydrate[Comparative Washing Test]

Under the conditions shown in Table 11, the cast rolled material S2 wassubjected to the acid washing (including water washing after acidwashing) and the caustic washing (including water washing after causticwashing) of the first step under the conditions shown in Table 10. Thewashing was performed by immersing the cast rolled material in thewashing liquid. The adjustment of the washing time was performed byadjusting the cast rolling speed. TABLE 11 Darkened portion Washingliquid Washing time removal rate % Comparative 50° C., 5 min 10 Example1 pH 13 sodium hydrate Comparative Room temperature, 5 min 10 Example 1pH 1 nitric acid

As to each surface washed cast rolled material, surface darkening wasobserved with naked eyes to obtain the removable rate. The darkenedportion removable rate is shown in each Table.

From the results shown in Tables 6 to 11, it is conformed thatmulti-stage washing including acid washing and caustic washing canremove the surface darkened portion of the cast rolled material.

Furthermore, continuous multi-stage washing was performed whileunwinding the rolled cast rolled material S2 at the same steps as inWashing tests A to E and Comparative washing test. As a result, it isconfirmed that similar washing effects can be attained to remove thedarkening.

Furthermore, the manufactured cast rolled material S2 was cut into smallpieces, and they were subjected to batch type immersing washing usingthe same washing liquids as in Washing tests A to E and ComparativeWashing test. As a result, it is confirmed that similar washing effectscan be attained to remove the darkening.

It should be understood that the wordings and expressions used hereinare used for the explanation purpose, should not be used to construe ina limited way, are not intended to exclude any equivalent of thefeatures described herein, and allow various deformation falling withinthe claimed scope of this invention.

INDUSTRIAL APPLICABILITY

The manufacturing method of the present invention makes the amount oflubricating oil to be supplied to a rotational molding memberappropriate during continuous casting, and therefore can be applied to acontinuous casting apparatus equipped with various rotational moldingmembers.

1. A method for manufacturing a metal material, characterized in that incontinuously casting a metal material by driving a plurality ofrotational molding members in a casting direction, the plurality ofrotational molding members being disposed so as to be opposed with eachother to form a casting space, wherein lubricating oil is intermittentlysprayed onto at least a part of a molten alloy contact surface of atleast one of the plurality of rotational molding members.
 2. The methodfor manufacturing a metal material as recited in claim 1, wherein theplurality of rotational molding members are a casting wheel having agroove on its external peripheral surface and a continuous belt forclosing the groove.
 3. The method for manufacturing a metal material asrecited in claim 2, wherein the lubricating oil is applied to the grooveof the casting wheel.
 4. The method for manufacturing a metal materialas recited in claim 3, wherein the lubricating oil is applied only to aside surface portion of the groove of the casting wheel.
 5. The methodfor manufacturing a metal material as recited in claim 2, wherein thelubricating oil is applied to the continuous belt.
 6. The method formanufacturing a metal material as recited in claim 1 or 2, wherein thespraying number of times T per second is set to V/(Lp+V×t) to 3V/(Lp+V×t), where V (mm/s) is a moving speed of a molten alloy contactsurface of the rotational molding member, t (s) is a single sprayingtime, Lp (mm) is a distance of a sprayed range in a casting direction,the sprayed range being formed by a single spraying in a state in whichthe rotational molding member is stopped.
 7. The method formanufacturing a metal material as recited in claim 1 or 2, wherein thespraying of the lubricating oil is performed by a plunger pump.
 8. Themethod for manufacturing a metal material as recited in claim 1 or 2,wherein a single spraying time is 0.001 to 1 s.
 9. The method formanufacturing a metal material as recited in claim 1 or 2, wherein asingle spraying amount is 0.001 to 1 ml.
 10. The method formanufacturing a metal material as recited in claim 1 or 2, wherein atotal spraying amount of the lubricating oil is 5 to 150 ml/h.
 11. Themethod for manufacturing a metal material as recited in claim 1, whereinsubsequent to the continuous casting, rolling is executed to manufacturea cast rolled material, and wherein the cast rolled material issubjected to multi-stage washing including acid washing or causticwashing.
 12. The method for manufacturing a metal material as recited inclaim 11, wherein the multi-stage washing is performed while moving thecast rolled material.
 13. The method for manufacturing a metal materialas recited in claim 12, wherein the multi-stage washing is performedsubsequent to the continuous casting and the rolling.
 14. The method formanufacturing a metal material as recited in claim 12, wherein themulti-stage washing is performed at a different step after thecontinuous casting and the rolling.
 15. The method for manufacturing ametal material as recited in claim 11, wherein the multi-stage washingis performed after cutting the cast rolled material.
 16. The method formanufacturing a metal material as recited in claim 11, wherein themulti-stage washing includes at least one caustic washing and at leastone acid washing.
 17. The method for manufacturing a metal material asrecited in claim 16, wherein the multi-stage washing is performed bycaustic washing and acid washing in this order.
 18. The method formanufacturing a metal material as recited in claim 16, wherein themulti-stage washing is performed by acid washing, caustic washing andacid washing in this order.
 19. The method for manufacturing a metalmaterial as recited in claim 11, wherein washing liquid for the acidwashing is any one of nitric acid, sulfuric acid and hydrochloric acid.20. The method for manufacturing a metal material as recited in claim11, wherein washing liquid for the caustic washing is sodium hydratesolution or potassium hydrate.
 21. The method for manufacturing a metalmaterial as recited in claim 11, wherein washing time for the acidwashing or the caustic washing is controlled by a time required for thecast rolled material to pass through each washing bath.
 22. The methodfor manufacturing a metal material as recited in claim 11, wherein thewashing bath passing time is set by a length of a washing bath in amoving direction of the cast rolled material.
 23. The method formanufacturing a metal material as recited in claim 21 or 22, wherein thewashing bath passing time is set by a serpentine distance along whichthe continuous cast rolled material is advanced in a washing bath. 24.The method for manufacturing a metal material as recited in claim 11,wherein water washing is performed after the acid washing or the causticwashing.
 25. An apparatus for manufacturing a metal material,comprising:a plurality of rotational molding members disposed so as to surround acasting space and driven in a casting direction; and a lubricating oilspraying means for intermittently spraying the lubricating oil to atleast a part of at least a part of the rotational molding members. 26.The apparatus for manufacturing a metal material as recited in claim 25,further comprising rolling means for rolling the cast material, therolling means being disposed at a rear stage of the rotational moldingmembers, and a plurality of washing baths including an acid washing bathwhich brings the rolled cast rolled material into contact with acidwashing liquid or a caustic washing bath which brings the cast rolledmaterial into contact with caustic washing liquid, wherein these washingbaths are disposed in series.
 27. The apparatus for manufacturing ametal material as recited in claim 26, wherein at least one acid washingbath which brings the cast rolled material into contact with the acidwashing liquid and at least one caustic washing bath which brings thecast rolled material into contact with the caustic washing liquid areprovided.
 28. A metal material manufactured by the manufacturing methodas recited in claim 1 or
 11. 29. A metal workpiece manufactured bysubjecting the metal member as recited in claim 28 to secondary working.30. The metal workpiece as recited in claim 29, wherein as the secondaryworking, plastic working or cutting work is executed.